Feb 20, 2009 · Anyone out there who can differentiate clearly the difference between interlock and permissive. This is referring to the use of these terms in PLC logic. Some logic have have got ready conditions, then permissive conditions and then interlock. Any standard out there which guides the use of these terms in PLC coding? Thank you indvance

Jun 12, 2010 · An interlock can also be a permissive, but a permissive is only a permissive. For instance, if I need the level in the tank to be above a certain point to start a pump, it is a permissive, if I also need that level to be above that same point to keep it running, now it has become an interlock.

Nov 27, 2002 · An interlock is a condition or series of conditions that must be met to allow an operation or process to continue. Examples are numerous, but some general examples include: shield interlock- the machine cannot run unless all the safety shields are closed flow interlock - the operation cannot continue unless the coolant flow is adequate

Jun 24, 2008 · The terms permissive and interlock are often used as a shutdown initiator. I regard a permissive as a condition required to reset a shutdown interlock. For some situations it could be the shutdown initiator. In other situations it could be a time delay, a reset button or other process situation required to reset the trip.

Jun 16, 2012 · Process Interlock : Something that prevents incorrect operation or possible damage to the process or equipment. Safety Interlock : Something that prevents possible damage or death to people operating that process or equipment. DCS and many PLC systems are not considered reliable enough for you to risk your life on.

Dec 8, 2004 · PERMISSIVE_D is the optional discrete input value and status that must be True when the Permissive device option is enabled to allow the device to be commanded to an Active state. INTERLOCK_D is the optional discrete input value and status that must be True when the Interlock device option is enabled for the device to remain in the Active state.

Feb 18, 2023 · To make things safer, you could even interlock valve status as permissive to normal control sequence. Valve proximity/position switches these days are more reliable than they were many years ago. In many companies, Operations staff and management have significantly more clout then Engineering, so focus your efforts on convincing Ops first.

Nov 5, 2002 · H = Hand = Manual/Local Start, Inhibit Auto (or allow Start/Stop Permissive if combined with Start/Stop PB station) O = Off = Manual/Local Stop, Inhibit Auto (and Inhibit Local Start/Stop if PB station is installed) A = Auto = Allow Start/Stop from Remote (inhibit Local Start/Stop PB Yes, HOA can* be used alone (without PB's) for Start/Stop ...

Mar 11, 2008 · Ah, But 7 psi is not required for the typical preaction system, a single interlock 7.3.2.1(1). Right? (2) is noninterlock, (3) is double interlock. The 7.3.2.3.2 reqt for 7 psi air doesn't apply to single interlock. And yet 7.3.2.3.1 still requires piping to be supervised. The only logical way to supervise the piping is with.. Compressed air.

Jun 17, 2014 · Here is my response to op: Think about what trip and interlock do and it will help you understand why they are used. A trip automatically stops equipment. Why would you do that? Yes - operation is out of bounds (anomaly). Examples of trip conditions: High current. Sometimes high temperature, high vibration. An interlock prevents something from ...